In the field of electronic circuit assembly, electronic components are often carried from a supply of such components to a specific location on a circuit board for attachment thereto. The components may be of several different types, one group of which is known as surface mount components. Surface mount components include, but are not limited to such things as memory chips, resistors, connectors, dual in-line processors (DIPS), capacitors, and gate arrays.
Surface mount components include a body having a plurality of leads that are formed in aligned rows. The rows typically project from at least two, and perhaps all four sides of a parallelepiped component body. The component body includes a major plane extending therethrough, which is generally parallel to the top surface and to the bottom surface of the body. One type of conventional surface mount component (such as that shown with reference to the present invention in FIG. 2) includes a row of leads that project from each of two opposed sides of the component body. The leads each extend outwardly for a first distance, downwardly for a second distance, and outwardly for a third distance. The lead portions extending for the third distance include the terminal ends of the leads, which are parallel to the major plane of the component body. A second type of conventional surface mount component (such as that shown in FIG. 4 with reference to the present invention) includes leads that project directly away from the body of the component. Again, the terminal ends of the leads each extend parallel to the major plane of the body of the component.
Rather than manually affixing each individual surface mount component to a circuit board, the electronics industry makes extensive use of robotic placement machines, which grasp a component at a specific location (the supply) and place it at another specific location (the circuit board). To ensure the sustained operation of such robotic placement machines, a continuous supply of electronic components must be furnished to the machine at a predetermined location in order that the robotic placement machine may be programmed to repeat a precise sequence of movements during every cycle. It is therefore important that each such component be located in the same position (i.e. the point at which the robotic placement machine grasps the component) as each preceding and succeeding component.
One way to provide a continuous supply of electronic components to a desired location is to provide a series of such components within spaced pockets of a carrier tape. The loaded carrier tape, which is usually provided in roll form, may then be advanced toward the pick-up location at a predetermined rate as each succeeding component is removed from the tape by the robotic placement machine. Conventional carrier tapes generally comprise a self-supporting lower portion that carries the component, and a flexible cover strip that aids in preventing foreign matter from deleteriously affecting the component. The cover strip is typically releasably bonded to the lower portion, (e.g. thermally, ultrasonically or adhesively), and is progressively peeled away from the lower portion just before the robotic placement machine removes the component from the carrier tape.
A conventional carrier tape 10 is shown in combination with a robotic placement machine 12 in FIG. 1. A supply roll 14 provides carrier tape 10 having an aligned plurality of regularly spaced pockets 16, each of which is loaded with a component. A stripper assembly 18 peels the cover strip 20 from carrier tape 10 around a stripper block 22, which assists in preventing stripper assembly 18 from pulling carrier tape 10 away from its designated path. Carrier tape 10 is advanced by a sprocket 24, which engages advancement holes along at least one outer edge of carrier tape 10 to advance carrier tape toward robotic placement machine 12. As each successive component reaches the desired pick-up point, the robotic placement machine grasps the component (either manually or by suction) and places it on a circuit board in the appropriate location.
One type of carrier tape that relates to the present invention is shown in U.S. Pat. No. 4,702,370 (Honda). The '370 patent discloses a carrier tape having a series of pockets for storage and delivery of electronic components. The walls of the pockets are formed to hold a component within, and include wall portions that act to retain each of the leads. The '370 patent further states that "[t] o store and hold such an IC or similar-shaped component . . . the shape of the recess 34 is determined in accordance with the greatest peripheral dimensions of this IC or similar-shaped component 40." Thus the carrier tapes of the prior art, as exemplified by the '370 patent, include pockets that are designed to match the size of the series of components to be packaged.
Carrier tapes generally, and the carrier tape of the '370 patent in particular are not intended to convey surface mount components of different sizes. As described above, known carrier tapes include pockets sized to match a particular series of components. In order to package components of different sizes, a packager would have to stock carrier tapes of different sizes, corresponding to each of the sizes of surface mount components that were to be packaged. Because there are dozens, or perhaps even hundreds of sizes of surface mount components, a component packager could be required to maintain a sizable inventory of carrier tapes, and incur the concomitant costs thereof.
In view of the disadvantages of conventional carrier tapes, it is therefore desirable to provide a carrier tape for surface mount components that can convey different types and sizes of surface mount components.